The heart of a computer is a magnetic hard disk drive (HDD) which typically includes a rotating magnetic disk, a slider that has read and write heads, a suspension arm above the rotating disk and an actuator arm that swings the suspension arm to place the read and/or write heads over selected circular tracks on the rotating disk. The suspension arm biases the slider into contact with the surface of the disk when the disk is not rotating but, when the disk rotates, air is swirled by the rotating disk adjacent an air bearing surface (ABS) of the slider causing the slider to ride on an air bearing a slight distance from the surface of the rotating disk. When the slider rides on the ABS, the write and read heads are employed for writing magnetic impressions to and reading magnetic signal fields from the rotating disk. The read and write heads are connected to processing circuitry that operates according to a computer program to implement the writing and reading functions.
The volume of information processing in the information age is increasing rapidly. In particular, HDDs have been desired to store more information in its limited area and volume. A technical approach to this desire is to increase the capacity by increasing the recording density of the HDD. To achieve higher recording density, further miniaturization of recording bits is effective, which in turn typically requires the design of smaller and smaller components.
The further miniaturization of the various components, however, presents its own set of challenges and obstacles. In recent years there has been rapid development in increasing the recording densities for magnetic disk recording and playback devices to meet the increase in quantities of data handled. A key issue in achieving high recording densities is a reduction in the magnetic spacing, which is the distance between the magnetic head slider and the magnetic disk. However, when the magnetic spacing is reduced, the magnetic head slider is more likely to contact or impact the magnetic disk surface which rotates at high speed. For this reason, in addition to a thin and durable protective film being formed on the ABS of the magnetic head slider, high resistivity to wear is also important.
At the same time, magnetic resistance elements mounted on the magnetic head slider suffer from the disadvantage that the magnetic materials are susceptible to corrosion, and the air bearing protective film (ABPF) also needs to be able to prevent corrosion of the magnetic materials. In addition, when there is a difference in potential between the magnetic head and the magnetic disk, there is a problem where a discharge may occur between the magnetic head slider and the magnetic disk, damaging the magnetic resistance elements, and it is thus desirable that the ABPF also have the ability to protect against electrical discharges.
To satisfy these desired properties, a thin film which leaves no dust during sliding, has a low coefficient of wear, superior wear resistance, a high atomic density, and is chemically stable is preferable.